THE INFLUENCE OF MICROWAVE-INCINERATED RICE HUSK ASH (MIRHA) ON INTERFACIAL ZONE CHARACTERISTIC AND CONCRETE PROPERTIES

Researchers have discovered that, rice husk ash (RHA), rich in silica can be utilized as cement replacement material (CRM) in the construction industries. Burning procedure to obtain RHA that is highly reactive and the optimum percentage replacement of OPC need to be identified. Improper burning with regards to procedures and maximum combustion temperature may result sub-standard RHA being produced. This research was carried out to investigate the effects of replacing 5%, 10%, 15% and 20% of cement in concrete by open burning RHA and microwave incinerated rice husk ash (MIRHA). The RHA was collected from two rice milling processes and both were using uncontrolled burning method meanwhile MIRHA was obtained using UTP Microwave Incinerator (UTPMI) in controlled temperatures of 600°C, 700°C and 800°C. X-Ray Diffraction (XRD) analysis was carried out to analyze the crystalline properties to detect the presence of crystal system of SiO2 and X-Ray Fluorescence (XRF) analysis was performed to determine the content of various chemical oxides in both samples. This research compared the performance of MIRHA, RHA and control OPC concretes with reference to their compressive strength, porosity and Interfacial Transition Zone (ITZ) characteristic. The strength developments of the various concrete mixes were monitored at ages 3, 7, 28 and 56 days. In general, it showed that 5% replacement of MIRHA burnt at 800°C provided good acceleration in compressive strength development and the lowest porosity at 28 days. The push-out test at 28 days curing revealed that 5% inclusion of MIRHA at 800°C burning temperature provided good interfacial bond strength of aggregate/mortar. Scanning Electron Microscopy (SEM) test disclosed that the replacement of this pozzolanic material could affect the ITZ between aggregate and cement paste by modifying the micropore structure within the concrete matrix.